The author of this content. Please note that author is special in that HTML 5 provides a special mechanism for indicating authorship via the rel tag. That is equivalent to this and may be used interchangeably.

The number of comments this CreativeWork (e.g. Article, Question or Answer) has received. This is most applicable to works published in Web sites with commenting system; additional comments may exist elsewhere.

The service provider, service operator, or service performer; the goods producer. Another party (a seller) may offer those services or goods on behalf of the provider. A provider may also serve as the seller. Supersedes carrier.

Indicates (by URL or string) a particular version of a schema used in some CreativeWork. For example, a document could declare a schemaVersion using an URL such as http://schema.org/docs/releases.html#v1.91 if precise indication of schema version was required by some application.

An additional type for the item, typically used for adding more specific types from external vocabularies in microdata syntax. This is a relationship between something and a class that the thing is in. In RDFa syntax, it is better to use the native RDFa syntax - the 'typeof' attribute - for multiple types. Schema.org tools may have only weaker understanding of extra types, in particular those defined externally.

Indicates a page (or other CreativeWork) for which this thing is the main entity being described.

Many (but not all) pages have a fairly clear primary topic, some entity or thing that the page describes. For
example a restaurant's home page might be primarily about that Restaurant, or an event listing page might
represent a single event. The mainEntity and mainEntityOfPage properties allow you to explicitly express the relationship
between the page and the primary entity.

Related properties include sameAs, about, and url.

The sameAs and url properties are both similar to mainEntityOfPage. The url property should be reserved to refer to more
official or authoritative web pages, such as the item’s official website. The sameAs property also relates a thing
to a page that indirectly identifies it. Whereas sameAs emphasises well known pages, the mainEntityOfPage property
serves more to clarify which of several entities is the main one for that page.

mainEntityOfPage can be used for any page, including those not recognized as authoritative for that entity. For example,
for a product, sameAs might refer to a page on the manufacturer’s official site with specs for the product, while
mainEntityOfPage might be used on pages within various retailers’ sites giving details for the same product.

about is similar to mainEntity, with two key differences. First, about can refer to multiple entities/topics,
while mainEntity should be used for only the primary one. Second, some pages have a primary entity that itself
describes some other entity. For example, one web page may display a news article about a particular person.
Another page may display a product review for a particular product. In these cases, mainEntity for the pages
should refer to the news article or review, respectively, while about would more properly refer to the person or product.
Inverse property: mainEntity.